1. Technical Field
The present disclosure relates to a fingerprint identification apparatus, in particular, to a fingerprint identification apparatus and biometric signals sensing method using the same.
2. Description of Related Art
Capacitive fingerprint sensors and optical fingerprint sensors are well known in the technical field of fingerprint identification. Generally, the capacitive fingerprint sensor is miniaturized for use on handheld devices, but its durability and sensitivity are gradually diminished as the chip is exposed to the outside and the capacitive fingerprint sensor may be affected by sweat and other external factors. As to the optical fingerprint sensor, it has been well developed, but optical elements are necessary for an optical fingerprint sensor, causing an optical fingerprint sensor to be hard to apply to handheld devices because of a bulky volume.
Capacitive fingerprint sensors are made by semiconductor manufacturing process. The capacitive structure and capacitive sensing circuit are integrated within a chip in which the capacitive sensing units are distributed in a high density for sensing fingerprint images. When a finger presses on the chip face, the distance difference between the fingerprint valleys and the fingerprint peaks of the finger and the capacitive sensing units may produce different capacitance values which are used to form a fingerprint image.
Optical fingerprint sensors are mainly formed of a light source, a dispersive prism, and a charge-coupled device (CCD). When a finger presses the dispersive prism, a fingerprint image could be obtained based on the absorption of the total reflection by the fingerprint valleys and the fingerprint peaks of the finger. The CCD can extract the fingerprint valleys and the fingerprint peaks of the finger to form the fingerprint image. As the finger is pressed upon optical elements, the optical fingerprint sensors could be relatively cost-effective and durable. Thus, the optical fingerprint sensors have been widely used in public places.
However, capacitive fingerprint sensors and optical fingerprint sensors are mainly used to sense fingerprint images, and neither of them can simultaneously sense fingerprint images and biometric signals. Different biometric signals need to be sensed by using different sensing techniques, but the sensing techniques cannot integrate capacitive fingerprint sensors and optical fingerprint sensors.